For eight years she headed the coronary care unit at the Johns Hopkins Hospital. At the medical school she served as assistant dean for post-doctoral programs and faculty development. During that time she organized a nationally covered Mary Elizabeth Garrett symposium on women in medicine which examined the opportunities and hurdles faced by women physicians roughly 90 years after the founding of the medical school in 1893, and at the same time honored Ms. Garrett, the Victorian socialite and philanthropist who made sure Johns Hopkins School of Medicine opened its admissions to women (the medical school opened its doors on October, 1893; and three of the eighteen original candidates for the M.D. degree were women) and ultimately admitted women and men precisely on the same terms.[2]

While at Johns Hopkins, Healy held several leadership positions in organizations such as the American Federation of Clinical Research, the American College of Cardiology, and the American Heart Association, an organization she later led as its volunteer president, and served on advisory committees to the National Heart, Lung and Blood Institute. The Age of Autism anti-vaccine group named her 2008 Person of the Year[3] for her support of the discredited[4][5] hypothesis that vaccines are linked to autism.

Healy was recruited away from Ohio State to become President and CEO of the American Red Cross in late 1999, succeeding Elizabeth Dole. From the outset she strove to unite the various services and volunteers under the banner "Together we can save a life."

Her tenure at the Red Cross was not without controversy. In the spring of 2001 the FDA issued a record fine to the Red Cross for mishandling CMV infected blood products.

The American Red Cross was criticized in the media, by New York State Attorney GeneralEliot Spitzer, and by some in Congress for designating funds for 9/11 related activities that did not directly involve victims. In fact, general funding was a long-standing Red Cross policy. The Red Cross was forced to change its policy.

Healy also advocated withholding dues from the International Red Cross for not supporting the Israeli Red Cross, and her hard-charging tendencies resulted in managers "losing control over day-to-day decision-making".[6] She was forced to resign in the wake of these controversies.[7][8][9][10] Dr. Healy departed the organization as president on December 31, 2001.

President Ronald Reagan appointed Healy deputy director of the White House Office of Science and Technology Policy. She served as chairman of the White House Cabinet Group on Biotechnology, executive secretary of the White House Science Council's Panel on the Health of Universities, and a member of several advisory groups on developing government wide guidelines for research in human subjects, and for the humane treatment of animals in research. She subsequently served on the President's Council of Advisers on Science and Technology during the administration of Presidents George H.W. Bush and George W. Bush.

Dr. Healy served from 1991 until June 30, 1993. Healy was the first woman director at NIH.

Healy was director of the Research Institute at the Cleveland Clinic Foundation when President George H. W. Bush tapped her in 1991 to become director of the NIH, its first woman head. She took on many initiatives during her two years at the helm, including the development of a major intramural laboratory for human genomics and recruited a world-renowned team to head the Human Genome Project, including current NIH director Dr. Francis Collins, elevated nursing research to an independent NIH institute, established a policy whereby the NIH would fund only those clinical trials that included both men and women when the condition being studied affects both genders. [11]

The Women's Health Initiative was a $625 million effort to study the causes, prevention, and cures of diseases that affect women at midlife and beyond. The study continues to unearth critical information, including evidence in 2002 that combined hormone replacement therapy increases the risk of invasive breast cancers by 26% and heart attack by 27% as well as an increased risk for stroke. The study's findings have resulted in a permanent 15% annual reduction in invasive estrogen positive breast cancer in post menopausal women in the U.S.; The HRT (hormone replacement) drug market in the United States simultaneously dropped by $1 billion, twelve months after the study's results were publicized, as 60% fewer women stopped filling their HRT prescriptions.[citation needed]

As president of the American Heart Association from 1988 to 1989, she sought to convince both the public and medical community that heart disease is also a woman's disease, "not a man's disease in disguise". Appointed president of the American Red Cross in 1999, Healy worked to improve the safety and availability of the American blood supply while overseeing the development of a Weapons of Mass Destruction response program. In 2001 she led the organization’s response to the September 11 attacks. [clarification needed]

In 1994, Healy was a Republican candidate to represent Ohio in the U.S. Senate. She ran in the GOP primary, and came in second in a four-person race. Lt. Gov. Mike DeWine won and prevailed in the general election.

In 1985 Healy left Washington and moved to Cleveland where she became Chairman of the Cleveland Clinic Research Institute and also practiced cardiology. In addition to building major new programs in molecular biology, neuroscience, and cancer biology, she headed a large NIH-funded research program in hypertension, and was the lead investigator for the Cleveland Clinic's participation in a major clinical research study comparing angioplasty with coronary artery bypass surgery. She headed the NIH advisory board for another multi-center clinical study that showed statins could slow course of atherosclerosis in coronary artery bypass grafts. During this time she initiated a medical student program in alliance with Ohio State University that served as a precursor to the founding of the Cleveland Clinic College of Medicine in 2004.[citation needed]

Healy served as professor and Dean of the College of medicine from 1995 to 1999. During her tenure, the college expanded its public health programs to become a School of Public Health, re-christening the College of Medicine into a College of Medicine and Public Health.

With her efforts, the medical school became designated as a National Center of Excellence in Women's Health. A new department of orthopaedics was created along with a planned development of a Musculoskeletal Institute. The James Cancer Center expanded its efforts in basic research with recruitment of Dr. Clara Bloomfield, an oncologist and leukemia researcher, and her husband Dr. Albert de la Chappelle, a world-famous geneticist; together, they expanded the college's programs in cancer research and tumor genetics. Cardiovascular research and practice grew with the recruitment of Dr. Robert Michler of Columbia University, who helped to revitalize the thoracic surgery and heart transplantation, and developed one of the earliest robotic heart surgery programs. Dr. Pascal Goldschmidt, a cardiologist and researcher, who was recruited from Johns Hopkins, helped create the Heart and Lung Institute.[citation needed]

Healy served on numerous medical advisory committees and boards over her career. They included committees of the National Academy of Science's Institute of Medicine, of which she is a member, and the national Academy of Engineering; the Department of Energy, NASA, and the National Institutes of Health. She participated briefly on an Advisory board of The Advancement of Sound Science Coalition (an organization later shown to have been funded by Philip Morris), and served on numerous advisory groups and Boards of the American Heart Association and the American College of Cardiology, where she was an outspoken critic of smoking and its effects on the cardiovascular system.[12]

Healy became the focus of controversy when she questioned the 2004 finding of the Institute of Medicine that the evidence refuting a link between childhood vaccinations and autism was conclusive. She suggested a government conspiracy against further research in a nationally televised CBS interview with Sharyl Attkisson.[14]

Healy was married to cardiac surgeon Floyd D. Loop,[15] a former CEO of the Cleveland Clinic. She and her husband had one daughter, Marie McGrath Loop. She had another daughter, Bartlett Bulkley, from her previous marriage.